Hot-blast stove



Patented Sept. 30, 1941 Andrew Bowland, Moun to William M. Baile of Pennsylvania t Lebanon, Pa., assigner i y Company, a corporation Application February 14, 1940, serial No. 318,958

(ci. 26a- 19) l Claims.

My invention relates to two-pass, side combustion type, blast furnace, hot-blast stoves. My

object is to construct such a stove in an eco` nomical manner and to provide it throughout with thermal insulation of properly graduated thickness, without introducing incidental troubles.

A specific example of my invention is illustrated by the accompanying drawing, in which:

Figure 1 is a vertical elevation, and

Figure 2 is a cross-section taken from the line II-II of Figure 1.

More specically, the drawing shows a stove having a steel shell made in the form of telescoped cylinders I, 2. 3 and 4 which progressively increase in diameter toward the hotter ends of the stoves combustion chamber 5 and its checkerwork 6. It is to be understood that gas is introduced in the lower end of the combustion chamber 5 and burns upwardly, the products of combustion exhausting into the dome l and passing downwardly through the checkerwork 6.

The cylindrical wall 8 of the chamber 5 and the cylindrical stove lining 9 merge to form a single wall section extending the height of the stove. The wall 8 of the chamber 5 is of a thickness throughout its height that is suiiicient to withstand the combustion reactions, so the mentioned section must be of similar thickness throughout its height.

A stove having a combustion chamber wall and lining made as described is more economical to construct than a stove having a combustion chamber wall entirely built inside of the stove lining so that a double-walled construction results at the point of tangency between the chamber wall and lining. At the same time, it introduces limitations insofar as concerns the provi. sion of thermal insulation which increases in thickness upwardly of the chamber where the hottest combustion reactions occur. However, the use of the telescoped cylinders herein described permits the provision of properly graduated thermal insulation I 0 inside the cylinders around the entire stove including both the exposed section of the wall 8 of the chamber and the stove lining 9,

Another feature of the stove is that the lining 9 is not reduced in thickness at its top, so the lining is of suflicient thickness from top to bottom to provide for travel of substantial amounts of heat from its hotter end to its cooler end by thermal conduction longitudinally of the lining. This is important because when relatively thick insulation protects the upper end of the lining properly support the dome against heat radiation, this end becomes eX- tremely hot, if theY heat does not escape in some manner, whereby the service life of the liningmay be too shortened to permit the use of the insulation to represent sound economy.

By the use of the telescoped steel cylinders as a stove shell to provide spacesv between this shell and the stove lining in which insulation may be applied which progressively increases in thickness toward the hotter end of the stove, it is unnecessary to reduce the thickness of the stove lining r9 toward the upper and hotter end oi the stove. I have found that the practice of reducing the thickness of the stove lining so as to provide greater space toward the hotter end of the` stove in which thermal insulation may be arranged is bad, because the stove lining at its hottest part is then of insufficient thickness to permit the conduction of suiiicient heat from this end of the lining to the cooler end.

Furthermore, this reduction in the thickness in the lining results in an inherently unstable construction, whereas a stove made in accordance with my invention is as strong as any stove can be made. 'Ihis practice of reducing the thickness of a stove lining is particularly objectionable when it is considered that while the structural strength of the lining is reduced, the lining at the same time is subjected to `undesirably high operating temperatures.

Attention is called to the fact that the dome 1 is made of brick and rests on the brick stove This dome is a heavy, complicated and expensive structure and if :the lining fails to the latter may shift in position or actually fall, great expense being involved in either instance. However, the lining 9 being of unreduced thickness provides a very stable brick supporting structure for the dome 7, this structure maintaining itself at safe operating temperatures for reasons already described, even though it is heavily insulated against heat loss by radiation. Maintaining the lining thickness clear to the stove top provides another advantage other than previously mentioned in that it permits the travel of substantial amounts of heat from the brick dome down the lining to the cooler parts of the stove. It is well known that stove domes are subjected to undesirably high operating temperatures and anything that tends to lower these temperatures is important.

It is to be understood that the wall 8 of the combustion chamber 5 and the stove lining 9 are constructed from bricks, which are relatively good heat conductors. Furthermore, although the usual air space between the conventional stove shell and lining, necessary to permit breathing of the stove, provides insulation against thermal losses by convection or conduction, this air space does not prevent high radiation losses, these representing the majority of the thermal losses ofthe stove and normally keeping the stove lining from attaining extremely high temperatures, due consideration being given the type of bricks used. The thermal insulation l0 used by my stove is asbestos block insulation or other material of a similar nature,

this providing good insulation insofar asradia-v tion losses are concerned.

I claim:

1. A two-pass, side combustiontypey blast furnace, hot-blast stove having a steel shell made in the form of telescoped cylinders whichlprogressively increase in diameter toward the hotter ends of the stoves combustion chamber and checkerwork and thewalls of saidrchamber and of the stove lining mergingto form a single wall section extending the height of the stove, said shell enclosing said lining including said section and providing an annular space around all that progressively increasesV toward said hotter ends and which is flledwith thermal insulation.

2. A two-pass, side combustion type, blast furnace, hot-bl-ast stove vhaving a steel shell made in the `form of telescoped cylinders which progressively increase in diameter toward the hotter ends of the stoves combustion chamber and checkerwork and the walls of said chamber and of the stove lining merging to form a single wall section extending the height of the stove, said shell enclosing said lining including said section and providing an annular space around all. that progressively increases toward said hotter ends and which is lled with thermal insulation, said lining being of unreduced thickness from top to bo*- tom to provide for the travel of substantial amounts of heat from the hotter end of said lining to its cooler end by thermal conduction longitudinally of said lining.

3. A two-pass, side combustion type, blast furnace, hot-blast stove having a steel shell made in the form of telescoped cylinders which progressively increase in diameter toward the hotter ends of the stoves combustion chamber and checkerwork, said lining being of unreduced thickness from top to bottom to provide for the travel of substantial amounts of heat from the hotter end of said lining to its cooler end by thermal conduction longitudinally of said lining, said shell enclosing said lining and providing an annular spacethat progressively increases toward said hotter ends and which is filled with thermal insulation.

4. A two-pass, blast furnace, hot-blast stove having a Icombustion chamber and checkerwork of substantiallyequal heights with a dome inter-V connecting their tops-and which Vare both `designed to operate at higher temperatures .at their upper portions than attheir lower portions, ya

stove lining surrounding both said chamber and said checkerwork, and a steel shell made in the form of telescoped cylinders which progressively increase in diameter toward the upper andlhotter portions of said chamber and said checkerwork, said shell enclosing said lining and vproviding an annular space therebetween which progressively increases in cross section toward said upper and hotter portions, said space being substantially lled with thermal insulation.

i ANDREW BOWLAND. 

